Detection of asymptomatic Leishmania infection in blood donors at two blood banks in Ethiopia

Author summaryVisceral leishmaniasis (VL) is a disease caused by Leishmania parasites. While predominantly transmitted by sandflies, cases of VL transmitted through blood transfusion have been reported, particularly in immunocompromised recipients. Whereas Leishmania parasites have been found in blood donors in VL endemic areas across the globe, this has never been studied in East-Africa. We studied how common Leishmania infections occur in blood donors presenting at two blood bank sites (Metema and Gondar) in northwest Ethiopia. Metema is located in a VL-endemic area; Gondar has historically been considered VL non-endemic but as an outbreak of VL has occurred around Gondar, it was defined as previously VL non-endemic. Blood samples were tested for the presence of the parasite (DNA) or antibodies against the parasite. Asymptomatic infection was defined as positivity on any of these tests in a healthy person. A total of 426 voluntary blood donors were included, predominantly young men living in urban areas. DNA or antibodies against Leishmania was detected in 15.0% in Metema and 4.2% in Gondar. There were six individuals with two positive tests: one positive on rK39 and PCR and five positive on rK39 and ELISA. The prevalence of asymptomatic infection was higher in Metema and males but was not associated with age, a history of VL amongst family members or living in a rural area. Antibodies against Leishmania and parasite DNA was detected in a substantial number of blood donors. Future research should be directed at better defining the risk to recipients, including parasite viability studies and longitudinal studies amongst recipients. Visceral leishmaniasis (VL) is a disease caused by Leishmania parasites. While predominantly transmitted by sandflies, cases of VL transmitted through blood transfusion have been reported, particularly in immunocompromised recipients. Although Leishmania parasites have been found in blood donors in some VL endemic areas, this has never been studied in East-Africa, where HIV prevalence is relatively high. We established the prevalence of asymptomatic Leishmania infection and associated socio-demographic factors among blood donors presenting at two blood bank sites (Metema and Gondar) in northwest Ethiopia between June and December 2020. Metema is located in a VL-endemic area; Gondar has historically been considered VL non-endemic but as an outbreak of VL has occurred around Gondar, it was defined as previously VL non-endemic. Blood samples were tested by the rK39 rapid diagnostic test (RDT), rK39 ELISA, direct agglutination test (DAT) and qPCR targeting kinetoplast DNA (kDNA). Asymptomatic infection was defined as positive by any of these tests in a healthy person. A total of 426 voluntary blood donors were included. The median age was 22 years (IQR, 19-28 years); 59% were male and 81% resided in urban areas. Only one participant had a history of VL and three had a family history of VL. Asymptomatic infection was detected in 15.0% (n = 32/213) in Metema and 4.2% (n = 9/213) in Gondar. The rK39 ELISA was positive in 5.4% (n = 23/426), the rK39 RDT in 2.6% (11/426), PCR in 2.6% (11/420) and DAT in 0.5% (2/426). There were six individuals with two positive tests: one positive on rK39 RDT and PCR and five positive on rK39 RDT and ELISA. The prevalence of asymptomatic infection was higher in Metema (VL-endemic) and males but was not associated with age, a history of VL amongst family members or living in a rural area. Antibodies against Leishmania and parasite DNA was detected in a substantial number of blood donors. Future research should be directed at better defining the risk to recipients, including parasite viability studies and longitudinal studies amongst recipients.